<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>布局</title>
</head>
<style>
  #box{
    width: 600px;
    height: 600px;
    background-color: #0bb20c;
    /*float: left;*/
  }

  #box > div:first-child {
    width: 200px;
    height: 200px;
    float: left;
    background-color:red;
  }

  #box > div:nth-child(2) {
    width: 300px;
    height: 200px;
    background-color: yellow;
    /*float: left;*/
  }

  #box > div:nth-child(3) {
    width: 200px;
    height: 200px;
    background-color: blue;
    /*float: left;*/
  }
  /*#box > div:last-child {*/
  /*  width: 400px;*/
  /*  height: 400px;*/
  /*  background-color: #000005;*/
  /*  clear: both;*/
  /*}*/
</style>
<body>
    <div id="box">
        <div>1111111
<!--          <div style="float: left;width: 10px">aaaaaaa</div>-->
        </div>
        <div>2222222
<!--          <div style="float: left;width: 100px">bbbbbbbb</div>-->
        </div>
        <div>3333333</div>
<!--        <div>4</div>-->
    </div>
</body>
</html>
